Loudspeaker

ABSTRACT

A loudspeaker comprising a plurality of side panels disposed uprightly with their side edges facing, and post means between the facing side edges of adjacent panels, each post having a pair of elongated grooves for receiving a pair of panel edges to define a polygonal housing, no two sides of which are parallel to each other, each post further including an elongated portion defining a support for a grill cloth disposed about the girth of said housing and adapted to space said grill cloth apart from each panel of the housing. A plurality of substantially identical speakers are mounted in at least three of the panels, about onefourth of the speakers facing forwardly of the loudspeaker and about three-fourths of the speakers facing generally rearwardly of the loudspeaker.

United States Patent [1 Carroll [451 Mar. 26, 1974 LOUDSPEAKER [76]Inventor: James C. Carroll, PO. Box 5301,

Knoxville, Tenn. 37918 [22] Filed: Dec. 20, 1972 [21] Appl. No.: 316,822

Primary ExaminerStephen J. Tomsky [5 7] ABSTRACT A loudspeakercomprising a plurality of side panels disposed uprightly with their sideedges facing, and post means between the facing side edges of adjacentpanels, each post having a pair of elongated grooves for receiving apair of panel edges to define a polygonal housing, no two sides of whichare parallel to each other, each post further including an elongatedportion defining a support for a grill cloth disposed about the girth ofsaid housing and adapted to space said grill cloth apart from each panelof the housing. A plurality of substantially identical speakers aremounted in at least three of the panels, about one-fourth of thespeakers facing forwardly of the loudspeaker and about three-fourths ofthe speakers facing generally rearwardly of the loudspeaker.

9 Claims, 4 Drawing Figures PATENTEDMARZES 1974 SHEET 1 OF 2 LOUDSPEAKERThis invention relates to loudspeakers and particularly to the physicalconstruction of such.

In the manufacture of loudspeakers, particularly those intended for usein home entertainment type applications, it is desirable that theloudspeaker provide optimum quality of sound yet be manufactured at acost such that it can be sold at a relatively low price. This strugglefor optimum sound at a low cost to the purchaser has existed in the artfor many years. Among the factors involved in the struggle are thoseelements affecting the quality of the sound such as the number and kindof speakers, the geometry of the speakers and their cabinet, e. g.acoustical coupling, etc., and those elements affecting the structuralquality, physical appearance and cost of the product such as itsstructural integrity when in use, the type and quality of materials ofconstruction, the mode of construction and assembly, etc.

It is an object of this invention to provide a loudspeaker having novelconstruction. Other objects and advantages will appear from thefollowing description including the drawings in which:

FIG. 1 is a front view, partly cutaway, of a loudspeaker includingvarious features of the invention;

FIG. 2 is a rear view of the loudspeaker of FIG. 1;

FIG. 3 is a top view of the loudspeaker of FIG. 1 with the top coverremoved;

FIG. 4 is a fragmentary representation, top view thereformofg cgrner ofthe loudspeaker of FIG. 3.

The loudspeaker of this disclosure includes a plurality of side panels,no two of which are parallel to each other, disposed in uprightpositions with the upright side edges of each panel disposed adjacentthe upright side edges of adjacent panels. The facing side edges ofadjacent panels are separated by an upright post having longitudinalgrooves in two of its adjacent sides for receiving the side edges of thepanels to define a hollow polygonal housing. One of the side panelsserves as the front of the loudspeaker and the two panels most nearlydiagonally opposite the front panel define the rear of the loudspeaker.A plurality of speakers is mounted in each of the two rear panels and inthe front panel. The speakers are substantially identical and preferablyabout one-fourth of the total number of speakers are mounted in thefront panel and three-eighths of the total number of speakers aremounted in each of the rear panels.

Each post of the housing includes an elongated portion that projectsoutwardly from the housing to define a support means for a grill clothdisposed about the girth of the housing. This support means maintainsthe grill cloth spaced apart from the housing so as not to developshadowing of the speakers. Top and bottom covers close the housing.

No removable fastening means is employed in assembling the panels totheir respective posts so that the elements of the loudspeaker do notloosen and induce undesirable baffle resonances when subjected to thevibration occurring during normal use. This is accomplished by employinga panel material which expands when wetted and wetting the side edge ofthe panel with adhesive prior to fitting it in its respective grooves ina post. The size and shape of each groove is chosen to be such that thegroove will receive an adhesivebearing panel edge, but, as the panelexpands, it presses against the sides of the groove with a forcesufficient to maintain the panel and post together while the adhesivecures or dries, thereby developing a good bond between the panel edgeand post.

With reference to the Figures, in one embodiment of the loudspeaker 10there is provided a front panel 12, side panels 14 and 16, and rearpanels 18 and 20. In the depicted embodiment, each of the five panels isof rectangular geometry and disposed in an upright position. Thedepicted panels are of substantially the same size and arranged withtheir vertical side edges 20 and 22 (panels 12 and 14, respectively, forexample) in juxtaposition to the side edges of adjacent panels so as todefine a hollow polygonal housing 23. The number, size and position ofthe several panels are chosen to insure that no two of the panels faceeach other on the inside of the housing so as to eliminate standingwaves between the speakers and the inside housing walls disposedopposite the speakers.

Each of the panels is of a rigid material that resists warpage qndprovides rigidity to the housing. The material preferably is readilyavailable at a relatively low cost. One suitable material is that knownin the building trade as particle board. This material comprises woodparticles, e. g., sawdust, pressed together and bonded with an adhesiveand is of relatively low cost. It exhibits good strength and can be cutand worked using conventional woodworking techniques and equipment. Woodalso can be used in the panels but is less desirable, principallybecause of its cost.

Upright posts 24, 26, 28, 30, and 32 are interposed between thejuxtaposed side edges of adjacent panels of the housing 23. The depictedposts are each of rectangular, preferably square, cross-section andoriented such that two adjacent sides 34 and 36 thereof face the sideedges 20 and 22 of the adjacent panels 12 and 14. Each of the sides 34and 36 of each post is provided with an elongated groove 38 and 40,respectively. Each groove is of a size and shape adapted to receive aside edge of a panel and is oriented within the post such that theadjacent panels 12 and 14, fitting in the grooves 38 and 40, forexample, define a selected angle A7 therebetween. In the depictedloudspeaker comprising five panels, this angle A7 is substantially 108degrees.

As shown in the figures, each post is oriented with re spect to thehousing 23 so that one corner edge of the post 24 is disposed outwardlyof the housing to define a substantially vertical elongated portion 42projecting from the housing to define a support for a grill cloth 44that encircles the girth of thehousing 23. Notably, such cornerelongated portion 420i each of the five posts in the depicted embodimentprojects outwardly from the housing by a distance sufficient to ensurethat such elongated portions hold the grill cloth spaced apart from thepanels sufficiently to permit the mounting of one or more speakers in apanel without the speaker being in contact with the grill cloth. In thismanner, the speaker is not shadowed on the grill cloth, a conditionwhich detracts from the desired appearance of the loudspeaker and lowersits quality. In one suitable embodiment, the elongated portions 42 ofthe posts project from the housing by a distance sufficient to space thegrill cloth 44 about seven-sixteenths inch from each panel. Thisdistance has been found satisfactory to prevent shadowing of a speakerthat is about one-eighth inch from the grill cloth at the closest point.In a preferred embodiment, the grill cloth begins and ends at that post28 disposed between the rear panels 16 and 18 so that the ends 39 and 41of the cloth may be hidden from view as by a covering strip 45 of L-shape cross section secured over the ends of the grill cloth and thepost 28. In the preferred embodiment, each corner post comprises acommon 1% inch by 1% inch, square cross section, length of wood,preferably hardwood. This material is readily available at a relativelylow price. By reason of the manner of positioning of the post disclosedherein, such material is caused to serve multiple functions with aminimum of cutting or other working of the material as it comes from thesupplier thereby minimizing the manufacturing cost of the presentloudspeaker. Such lower cost does not sacrifice quality, but rather bymeans of the present techniques, the quality of the loudspeaker isimproved, particularly its stability and durability in service and itsphysical appearance.

The housing 23 is assembled by joining the panels to the posts.Rigidityof the loudspeaker housing 23 has been found to be obtainablewithout the use of nails, screws or the like in joining the panels andposts. This is achieved by applying liquid adhesive to the upright sideedges of the several panels, inserting the edges into their respectivegrooves in the posts, and clamping the assembly as by ring clamps aboutthe girth of the housing. As the adhesive is absorbed by the particleboard, the board expands. The sides 46 and 48 of the expanding paneledge bear against the sides 50 and 52 of the groove in which the paneledge resides and develops a pressure that ensures a good bond betweenthe panel edge and the post. The clamping rings are retained about theassembly until such bonds are substantially completed, usually afteronly a few minutes. This assembly procedure is simple, inexpensive andproduces joints that are superior in strength and rigidity to jointsobtained by conventional methods. The procedure further provides forrapid assembly thereby helping to produce the loudspeaker at a low cost.Several adhesives provide the desired bond between the panels and posts.Casein base adhesives have been found particularly suitable.

Top and bottom covers 72 and 74, respectively, are

provided to close the ends of the housing 23. These covers preferablyseal the ends of the housing so that the housing is substantially airtight" thereby provid-.

ing for the establishment of acoustical coupling of the several speakersinteriorly of the housing and accompanying enhancement of theircollective output.

Quality sound from the loudspeaker is obtained through the use ofmultiple, substantially identical, speakers 54 mounted in the panels l2,l6 and 18. The preferred speaker includes a mounting rim 56 and isinserted in an appropriately sized opening 58 in the panel 12, forexample. The speaker 54 is inserted into its opening 58 from the outsideof the housing 23 so that the rim 56 butts against the panel 12 when thes eaker is fully inserted. Each speaker is secured to its panel as byscrews 60. This procedure causes the speaker to fill the opening 58 inthe panel and positions the speaker face 62 outwardly of the plane ofthe panel so that there is no unfilled portion of the opening of thepanel that will develop a shadow on the grill cloth. This constructionfeature of the disclosed loudspeaker is in large part made possible bythe fact that the grill cloth is spaced apart from the panel, henceapart from the speaker, as referred to above. The cone (FIG. 1) of eachspeaker faces outwardly of the housing.

In a preferred embodiment, each loudspeaker includes sixteen individualspeakers 54 each of which is substantially identical to the otherspeakers in the system. Preferably, four of the speakers are mounted inthat panel 12 of the housing which faces a listener and defines thefront of the loudspeaker. These four speakers develop about one-fourthof the total sound energy output of the loudspeaker so that aboutone-fourth of the sound energy is radiated from the front of theloudspeaker. Each of the two panels 16 and 18 most nearly diagonallyopposite the front panel 12 are each provided with six speakers so thatabout three-fourths of the total sound energy from the loudspeakersystem is radiated from the rear of the loudspeaker.

For obtaining stereophonic listening effect, the present loudspeakersare employed as a pair, that is, two of the present loudspeakers aredisposed within a room and spaced apart from each other by a distance ofabout six feet with their fronts facing in the same direction and withtheir rear panels generally facing a wall of the room within which thespeakers are located. The loudspeakers are spaced apart from the wall byabout 12 18 inches. The pair of speakers thus employs a total of 32individual speakers, each of which is substantially identical to eachother speaker to provide stereophonic listening. This combination of 32speakers disposed in two separated loud-speakers, each of which contains16 speakers and having the indicated ratio of forward to rearwardradiated sound energy, in rooms of less than about 500 square feet floorarea, has been found to provide sound emanating from the speakers whichsubstantially completely fills the room. The result is that the soundappears to be coming from all points of the room. This effect has beenparticularly evident in rooms of about 200 square feet which appears tobe a common room size in a home entertainment center.

Contrary to the prior art teaching that 87 percent of the sound energyreceived by a listener in the concert hall should be received asreflected or deflected sound energy and that the remainder of the soundenergy should be received directly by the listener, the present inventorhas found that these concepts are not applicable to home entertainmentlistening, in part because of the very large number of absorptivesurfaces in a home as compared to a concert hall, and in part because ofthe appreciably greater size of a concert hall as compared with thecommon home entertainment center. In the latter, there is considerablyless volume to be permeated by the sound emanating from the loudspeakersand there is more opportunity for deflecting, reflecting and/orabsorbing of the sound by reason of the more closely spaced walls,ceiling, floor, and soundabsorbing objects within the room containingthe loudspeakers. It has been noted that in such home entertainmentenvironments, it is common to obtain dead spots" which appear to be theresult of improper distribution of the sound energy from theloudspeakers from which the music or other sounds emanate. In accordancewith the present invention, an especially large number of identicallysized speakers has been found to produce a like large num ber of pointsof origin for the sound, each of the origins being of the sameproperties (that is, having the same energy output) and being directedagainst various reflective surfaces within the room with the result thatthe listener obtains a substantially uniform quality and density ofsound at substantially any point within the room. This effect has beenfound to be obtained with the 32 speakers found in a pair ofloudspeakers each of which has 16 speakers as referred to above. If lessthan about percent of the sound energy is radiated from the front of theloudspeaker to the listening area, there is an overriding proportion ofthe reflected sound energy reaching the listener and he experiences adistorted sound which may take the form of an unrealistic reproductionof the sound produced by the loudspeaker. Greater percentages of soundradiated from the front of the loudspeaker also produce a distortedversion of the reproduced sound but of an opposite character. For example, greater than about percent forwardly radiated sound will result inunnatural sound dispersion in the room. A like problem exists when anexcessive portion of the sound energy is radiated from the rear of theloudspeaker. In addition, the surfaces in a home entertainment centerpossess widely varying sound absorption characteristics. The disclosedloudspeaker has been found to provide that distribution of sound energyoutput which tends to overcome the loss of portions of the sound energydue to varying degrees of sound absorption by surfaces in the room.

The use of a plurality of substantially identical speakers within asingle housing increases the probability of acoustical coupling betweentwo or more of the speakers and reduces the amplitude of undesirablesound resonances in the free air response of the drivers. This potentialproblem is eliminated in the disclosed loudspeaker by the use ofnonparallel side panels as referred to above. Accordingly, in thepresent speaker, the number and size of the panels used in themultisided housing are chosen to preclude the speakers mounted in onepanel from being oriented directly opposite and in alignment with one ormore of the other speakers. As noted, this is accomplished through theuse of an uneven number of equally sized panels, five such panels beinga preferred number. Fewer or more panels increase the difficulty andcost of assembly and- /or establishment of the desired spacing of thegrill cloth from the panels in the manner disclosed hereinbefore.

As desired, the polygonal housing may be filled with an acousticallyabsorbing material that will eliminate the interaction among theindividual speakers at frequencies above a few hundred Hertz.

lt is noted that through the use of the disclosed techniques for bondingthe panels to the posts, there is a substantial larger area of gluedsurface at each corner. This is in contrast to the glued mitered jointsemployed heretofore.

While a preferred embodiment has been shown and described, it will beunderstood that there is no intent to limit the invention by suchdisclosure, but rather, it is intended to cover all modifications andalternate constructions falling within the spirit and scope of theinvention as defined in the appended claims.

What is claimed is:

l. A loudspeaker adapted to mount a plurality of speakers within asingle enclosure comprising five side panels disposed in an upstandingposition,

with the vertical side edges of each panel disposed contiguous to thevertical side edges of adjacent panels to define a hollow polygonalhousing having no two upright sides thereof parallel to each other,

a plurality of elongated post means, each disposed between contiguousside edges of adjacent panels, means defining an elongated slotextending along each of the adjacent sides of each of said post means,each of said contiguous side edges of said adjacent panels on oppositesides of each of said post means being received in one of said slotmeans, each of said post means including an elongated portion projectingoutwardly from said housing to define a support means for grill clothmeans,

grill cloth means disposed about the periphery of said housing incontact with said support means of each post means whereby said grillcloth is held spaced apart from said side panels, and

top and bottom closure means disposed on opposite ends of said housing.

2. The loudspeaker of claim 1 and including a plurality of substantiallyidentical speakers, about one-fourth of-which are mounted in a panelfacing a listener and defining the front of said loudspeaker, and aboutthreeeighths are mounted in each of those two panels most nearlydiagonally opposite said front panel whereby said speakers in said rearpanels are directed away from a listener.

3. The loudspeaker of claim 2 wherein said grill cloth begins and endsat that post disposed between the adjacent side edges of the two mostrearward panels which serve as mounting means for those speakersdirected rearwardly of said loudspeaker.

4. The loudspeaker of claim 3 and including an elongated strip ofgenerally L-shaped cross section disposed over the ends of said grillcloth.

5. The loudspeaker of claim 1 wherein said panels defining saidpolygonal housing are of substantially the same size.

6. The loudspeaker of claim 1 wherein said post means are substantiallyidentical to each other and each possesses a substantially square crosssection, one elongated corner of which projects outwardly from saidhousing.

7. The loudspeaker of claim 1 and including adhesive means disposedalong each of the side edges of said panels and adapted to bond saidpanels to said post means.

8. The loudspeaker of claim 7 wherein each of said panels comprisesparticle board which expands when said adhesive is applied thereto.

9. in a loudspeaker of the type particularly useful in homeentertainment centers and adapted to house a plurality of speakers, amajority of which are positioned to direct their sound energy alongindirect paths to a listener and less than a majority of which arepositioned to direct their sound energy along direct paths to saidlistener, the improvement comprising a plurality of side panels disposedin upstanding position, with the vertical side edges of each paneldisposed contiguous to the vertical side edges of adjacent panels todefine a hollow polygonal housing having no two upright sides thereofparallel to each other and providing means for mounting said speakerssuch that no speaker has opposite its mounting panel another parallelplane to establish standing waves,

a plurality of elongated post means, each disposed between contiguousside edges of adjacent panels,

grill cloth means disposed about the periphery of said housing incontact with said support means of each post means whereby said grillcloth is held spaced apart from said side panels and out of contact withsaid speakers, and,

top and bottom closure means disposed on opposite ends of said housing.

1. A loudspeaker adapted to mount a plurality of speakers within asingle enclosure comprising five side panels disposed in an upstandingposition, with the vertical side edges of each panel disposed contiguousto the vertical side edges of adjacent panels to define a hollowpolygonal housing having no two upright sides thereof parallel to eachother, a plurality of elongated post means, each disposed betweencontiguous side edges of adjacent panels, means defining an elongatedslot extending along each of the adjacent sides of each of said postmeans, each of said contiguous side edges of said adjacent panels onopposite sides of each of said post means being received in one of saidslot means, each of said post means including an elongated portionprojecting outwardly from said housing to define a support means forgrill cloth means, grill cloth means disposed about the periphery ofsaid housing in contact with said support means of each post meanswhereby said grill cloth is held spaced apart from said side panels, andtop and bottom closure means disposed on opposite ends of said housing.2. The loudspeaker of claim 1 and including a plurality of substantiallyidentical speakers, about one-fourth of which are mounted in a panelfacing a listener and defining the front of said loudspeaker, and aboutthree-eighths are mounted in each of those two panels most nearlydiagonally opposite said front panel whereby said speakers in said rearpanels are directed away from a listener.
 3. The Loudspeaker of claim 2wherein said grill cloth begins and ends at that post disposed betweenthe adjacent side edges of the two most rearward panels which serve asmounting means for those speakers directed rearwardly of saidloudspeaker.
 4. The loudspeaker of claim 3 and including an elongatedstrip of generally L-shaped cross section disposed over the ends of saidgrill cloth.
 5. The loudspeaker of claim 1 wherein said panels definingsaid polygonal housing are of substantially the same size.
 6. Theloudspeaker of claim 1 wherein said post means are substantiallyidentical to each other and each possesses a substantially square crosssection, one elongated corner of which projects outwardly from saidhousing.
 7. The loudspeaker of claim 1 and including adhesive meansdisposed along each of the side edges of said panels and adapted to bondsaid panels to said post means.
 8. The loudspeaker of claim 7 whereineach of said panels comprises particle board which expands when saidadhesive is applied thereto.
 9. In a loudspeaker of the typeparticularly useful in home entertainment centers and adapted to house aplurality of speakers, a majority of which are positioned to directtheir sound energy along indirect paths to a listener and less than amajority of which are positioned to direct their sound energy alongdirect paths to said listener, the improvement comprising a plurality ofside panels disposed in upstanding position, with the vertical sideedges of each panel disposed contiguous to the vertical side edges ofadjacent panels to define a hollow polygonal housing having no twoupright sides thereof parallel to each other and providing means formounting said speakers such that no speaker has opposite its mountingpanel another parallel plane to establish standing waves, a plurality ofelongated post means, each disposed between contiguous side edges ofadjacent panels, means defining an elongated slot means extending alongeach of two adjacent sides of each of said post means, each of saidcontiguous side edges of said adjacent panels on opposite sides of eachof said post means being received in one of said slot means, and each ofsaid post means including an elongated portion projecting outwardly fromsaid housing to define a support means for grill cloth means, grillcloth means disposed about the periphery of said housing in contact withsaid support means of each post means whereby said grill cloth is heldspaced apart from said side panels and out of contact with saidspeakers, and, top and bottom closure means disposed on opposite ends ofsaid housing.